Vulcanization of rubber



T No Drawing.

Patented May 9, 1933 UNITED STATES PATENT OFFICE WITNFIE LD SCOTT, OF. NITRO, WEST VIRGINIA, ASSIGNOR TO THE RUBBER SERVICE 3 LABORATORIES 00., OFAKRON, OHIO, A CORPORATION OF OHIO VULCANIZATION F RUBBER The present invention relates to the vulcanization of rubber by an improved process wherein the products obtained by reacting a carbon disulfid derivative of a primary or secondary amine with a nitro or a nitro and halogen substituted derivative of a halogen phenyl mercaptan is employed as a vulcanization accelerator. The manufacture of the preferred class of accelerating compounds and their use in a rubber mix will be readily understood from the following description and examples. l i Y r The amine salts of alkyl-di-thiocarbamic acids, as are well known, are produced by the action of carbon disulfid on primary or secondary aliphatic amines and are accelerators of the vulcanization process. It has now been found that such amine salts or alkali salts of alkyl-di-thiocarbamic acids can be combined with a nitro substituted derivative of a halogen phenyl mercaptan to produce a stable compound having the general formula wherein It represents aliphatic hydrocarbon groups and R represents a nitro substituted aryl group. Such compounds have been found to be activeas accelerators of vulcanization when employed in a rubber mix and produce rubber products in a short period of time that possess high tensile strengths and other desirable characteristics required in commercial practice. a

Application filed August 29, 1928. Serial No. 302,890.

by dissolving substantially two molar portions of piperidine (17 0 parts) in ethyl alco hol. To this alcoholic solution of piperidine approximately one molar portion of carbon disulfid (7 6 parts) was added slowly at room temperature. To the alcoholic solution of piperidine pentamethylene dithiocarbamate thus prepared, substantially one molar portion (190 parts) of o-nitrophenyl chlormercaptan was added thereto with agitation at a temperature of approximately 20 to C. After the additionof the o-nitrophenyl chlormercaptan was completed, agitation was continued for about three hours at a temperature of substantially 20 to 50 C. The yellow solid formed, comprising the desired material, was filtered off, washed with alcohol and dried at about 50 C. This material, which is soluble in alcohol, benzene and chloroform, 1

has a melting point of substantially 123.8 to 124.3 C. andis most probably formed from piperidine pentamethylene dithiocarbamate and o-nitrophenyl chlormercaptan according to the following equation:

If prepared from the sodium salt of pentamethylene dithiocarbamic acid as hereinafter stated, the formation of the desired material most probably takes place according to the following equation:

Tothe sodium salt of penta'methylene dith-iocarbamic acid thus formed, approximately one molar portion of o-nitrophenyl chlorinercaptan (190 parts) was added at about 50 C. After the addition of'the o-nitrophenyl chlormeroaptan was completed, the "reaction mixture was stirred for an additional period of about four hours at approximately 50 C. The reaction product. was then'filtered off, washed with water to eliminate the sodium chloride formed as a by-product, and dried at about 50 C. i

Other alkyl-dithiocarbamic acids have been reacted in the manner hereinbefore set forth with a nitro chlor phenyl mercapt'anand products obtained which were found to be desirable for use in the preferred process as are hereinafter set forth. 1

Portions of the products hereinbefore described were incorporated in the ordinary manner into a rubber comprising Ifarts Pale crepe rubber 100 Sulfur 2 Zinc oxide 5 Accelerator, that is the piperidine pentamethylene dithiocarbamic reaction product of o-nitrophenyl chlormercaptan 1 0.5

Other mixes were likewise prepared in 60 which the quantity of sulfur used in the ex- 65 tions indicated in the fo l wing table n w ch are set forth the physical characteristics of the cured rubber stocks.

Modulus of elasticity Parts at elongation of g g f Tune of cure at elqnga 300% 500% 700% break. tlon 2 5 min. at 40 lbs. 153 276 862 2025 850 1. 75 steam pressure 153 273 781 2175 880 1.5 y 122 207 601 1905 913 2. 153 309 1015 2540 800 2.0 15 min. at 40 lbs. 229 507- 1850 3040 795 1.75 steam pressure 1 201 421 1520 2720 803 1. 5 196 894 1335 2825 825 2.25 245 568 2000 3590 800 2. 0 min.'at 40 lbs. 211 858 1615 3035 810 1. 75 steam pressure 190 374 1210 2555 820 1. 5 y 103. 320 979 2540 800 2. 25 244 534 1900 3435 803 2. 0 min. at 40 lbs. 187 392 1260 2435 820 1. 75 steam pressure 157 338 996 2240 825 Tests with other samples of the same rubber mix have shown that a fully'cured-product is obtained at lower temp'eraturesby heating the stocks ina press maintained'under lower steam pressures for slightlylonger periods than areset forth above.

The reaction product of the piperidine salt of pentameth'ylene dithiocarbamic and o-nitrophenyl chlormercaptan has also been tested in a'jrubloer f-ormula typ ical of a commercial treadstock. Sucha compound comprises Smoked sheet rubber A; h 27.85 Pale crepe rubber 26.15 Zinc oxide 15.0 Carbon black 25.0 Mineral rubber 1.0- A blended mineral oil and rosin 1,0 Stearic acid 1.0 Sulfur 1.9 Accelerator .5

Modulus of i I elasticity at Tenslle m. Part5. elongations of mate accel 'Ilme of cure lbs/1n 610B erator i at g r break 5 v E 300% 500% 1 0.5 5 min. at 40 lbs. steam 649' 1600 2675 680 0,2 pressure I I 341 .1 774 480 0.5 1:1 min. at 40 lbs. steam 1360 3040 3780 010 0.2 pressure 1 1 751 1785 2850 660 0.5 30 min at 401bslsteam "1280 3420 3755 550 0.2 pressure 1 3 866 2080 3200 650 0.-5 45min. at 40 111s. steam 4 1590 3400 3705 540 0.2 I pressure r 962 2300 3370 050 0.5 min. at 40 lbs. steam 1615 3380- '3710 550 0.2 pressure 990 2365 3285 610 0.5 120 min a t40 lbs. steam I 1335 2880 3010 I 550 0. 2 pressure 1055 2440 2930 055 Modulus of Parts .elelasticity atf f m. aceel- Time of cure e Ongatwns 0 lbs/in 5:? crater: at g break 0.5 20 min. at 20 lbs. steam 1075 2490 3775 000 0. 2 pressure 539 1330 24% 080 0.5 40 min. at 20 lbs. steam 1415 3255 4018 000 0. 2 pressure 760 1920 3175 080 0.5 50 min. 50,20 lbs. steam 1570 3455 3905 500 0. 2 pressure 883 2120 3305 090 0. 5 30 minual; 10 lbs. steam 000 1525 2525 700 0.2 pressure 224 559 490 0.5 00 min. at 10 lbs. steam 1235 2875 4040 080 0.2 pressure 1 038 1590 2860 090 0. 5 min. at 10 lbs. steam 1850 3710 4000 540 0.2 pressure 027 2245 3480 070 0.5 180 min. at 10 lbs. steam i 1980 3860 3900 523 0. 2 pressure 1100 2480 3050 620 Another of the preferred class of compounds, for example the reaction product of o-nitrophenyl chlormercaptan and diethyl.

amine diethyl dithiocarbamate, was prepared in an analogous manner to the reaction procluct of o-nitrophenyl chlormercaptan and piperidine pentamethylene dithiocarbarnate hereinbefore mentioned.

A sample of this material was incorporated in the usual manner in a rubber mix comprising i v Parts Pale crepe rubber 100 Sulfur 2 Zinc oxide 5 Accelerator 1 0.5

lowing table.

. Modulus of elasticity at elonga- T215118 m.

Parts tions of mate accel- Time of cure lbs/1n 910;

crater A at A 2 break non 0. 5 00 min. at 10 lbs. steam 159 311 1013 2870 890 0. 4 pressure 124 233 649 2330 940 0. 3 130 210 627 2170 938 0. 5 30 min. at 20 lbs. steam 109 358 1205 2070 838 0. 4 pressure 130 278 780 2410 910 0. 3 120 208 577 1930 930 0. 5 00 min. at 20 lbs. steam 210 491 1040 3200 813 0. 4 pressure 201 422 1410 3355 850 0. 3 185 371 1240 2805 850 0. 5 15 min. at 40 lbs. steam 201 398 1355 2850 835 O. 4 pressure 171 334 1000 2790 S08 0. 3 149 285 872 2405 888 0.5 30 min. at 40 lbs. steam 199 400 1170 2720 845 0. 4 pressure 188 359 1040 2910 878 0.3 182 318 950 2445 863 Qther examples of the preferred class of compounds, for example, the reaction procluct of dinitro-phenyl chlormercaptan and piperidine pentamethylene dithiocarbamate and the reaction product of chlor-nitroph-enyl chlormercaptan and normal dibutyl amine dibutyl dithiocarbamate Were incorporated in a rubber mix comprising Parts Pale crepe rubber 100 Zine oxide 5 Sulfur 3.5 Accelerator .3

Modulus of elasticity in ACOEL Time i lbs/in at clongations of rq Hater of cure lbs sile at tion at min. steal'n break break A 30 10 123 205 850 2200 890 B 30 10 123 191 400 1345 970 A 00 10 228 470 1545 3000 830 B 00 10 106 383 1205 2845 800 .A 30 20 304 1120 2410 838 B 30 20 162 309 800 2280 870 A 00 20 210 432 1455 3035 825 B 60 20 225 183 1700 3255 815 A 15 40 178 308 1045 2580 800 B 15 40 105 350 1005 2520 850 A 30 40 176 396 1115 2635 800 B 30 40 243 514 1570 3095 815 A 45 40 191 100 1000 2715 800 B 15 40 231 539 1075 3000 800 Nitro substituted derivatives of halogen phenyl mercaptans react with compounds other than the salts of alkyl dithiocarbamic acid to form an important group of compounds.

Other examples of the use of the preferred accelerators in the rubber vulcanization process are apparent to those skilled in the art. It is to be understood that different ingredicuts and different proportions of ingredients from those particularly set forth in the examples may be employed. 1

What is claimed is:

1. The process of manufacturing vulcan ized rubber which comprises combining with rubber a vulcanizing agent in the presence of an accelerating compound formed by reacting a carbon disulfid derivative of a secondary aliphatic amine with a nitro substituted derivative of a halogen phenyl mercaptan compound free of aromatic acyl substituents.

2. The process of manufacturing vulcaniZed rubber which comprises combining with rubber a vulcanizing agent in the presence of an accelerating compound formed by reacting acarbon disulfid derivative of a secondary aliphatic amine with a nitro substituted derivative of a chlor'phenyl mercaptan free of aromatic aicyl substituents. I

3. The process of manufacturing vulcan ized rubber which comprises combining with rubber aivulcanizing agent in the presence of an accelerating compound. formed by reacting a carbon disulfidderivative of a secondary aliphaticamine with o-nitrophenylchlormercaptan. J

4:. The process of'nianufacturing vulcanized rubber which comprises combining with rubber a vulcanizing agent in the presence oian accelerating compound formed by reacting an amine salt of an alkyl substituted dithiocarbamic acid with o-nitrophenyl chlormercaptan. I

5, The process or" manufacturing vulcanized rubber which comprises combining with rubber a vulcanizing agent, in the presence of an accelerating compound formed by reacting piperi-dine pentamethylenedithiocarbamate with o-nitrophenyl chlormercaptan.

6. The process of manufacturing vulcanized rubber which comprises combining with rubber a vulcanizing agent in the presence of an accelerating compound formed by reacting substantially equi-molar portions of piperidine pentamethylene dithiocarbamate and o-nitrophenyl chlormercaptan.

7. The vulcanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerator, said accelerator comprising the reaction product of a carbon disulfid derivative of an aliphatic amine with a nitro substituted derivative of a halogen phenyl mercaptan free of acyl substituents. v

8. The "vulcanized rubber product ob tained bywtreating rubber with a vulcanizing agent in the presence of an accelerator, said accelerator comprising the reaction product of a carbon disulfid derivative of a secondary aliphatic amine with a nitro substituted derivative of a halogen phenyl mercaptan compound free of aromatic acyl substituents. I V

9. The. vulcanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerator comprising the reaction produ'ct'of a carbon disulfid derivative of a secondary aliphatic amine with a nitro substituted derivative of a-chlor-phenyl mercaptan free oi aromatic acyl substituents. V v

10. The vulcanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerator, said acceleratorcomprising the reaction product of a carbon disulfid derivative of .a secondary aliphatic amine with o-nitrophenyl chlormercaptan.

- 11. The vulcanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerating compoundformed by reacting an amine salt of an alkyl substituted dithiocarbamic acid with o-nitrophenyl .chlormercaptan.

. 12. The vulcanized rubber product ob tained by treating rubber with a vulcanizing agent in the presence of an accelerating compound formed by reacting piperidine pentamethylene dithiocarbamate with o-nitrophenyl chlormercaptan'. T I 18. The vulcanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerating compoundformed by reacting substantially equi-molar portions of 'piperidine pentanyl chlormercaptan.

14a. The process of manufacturing vulcanizing rubber which comprises combining with rubber a vulcanizing agent in the presence of an accelerating compound formed by reacting a salt of'a ,dialkyl substituted dithiocarbamic acid with o-nitrophenyl chlormercaptan. 1 v

15. The vucanized rubber product obtained by treating rubber with a vulcanizing agent in the presence of an accelerator, said accelerator comprising the reaction product of a salt of a dialkyl substituted dithiocarbamic acid with'o-nitrophenyl chlormercaptan.

16. The process of manufacturing vulcanizedrubber which comprises combining with rubber a vulcanizing agent in the presence of anaccelerating compound formed by reacting a salt of an akyl substituted dithiocarbamic acid with a nitro substituted derivative of a halogen phenyl mercaptan compound free of other substituents.

' 17. The vulcanized rubber pro-duct obtained by treating rubber with a vulcanizing agent in the presence of anaccelerator, said accelerator comprising the reaction product of a salt of an alkyl substituted dithiocarbamic acid with a nitro substituted derivative of a halogen phenyl mercaptan compound free of other substituents.

In testimony whereof I hereunto aflix my signature. WINFIELD SCOTT.

methylene dithiocarbamate and o-nitrophe- 4 

